The invention discloses a low-nitrogen burner combusting mixed rotational flow lean gas/combustible gas and belongs to the technical field of thermal energy and power engineering. The low-nitrogen burner comprises a central pipe, wherein a combustible gas sleeve and an air sleeve are sequentially arranged on the periphery of the central pipe in a sleeving manner; one end of the central pipe is sealed; the central pipe communicates with the combustible gas sleeve through fin guide plates; the sealed end of the central pipe corresponds to openings of the combustible gas sleeve and the air sleeve; the fin guide plates comprise two parallel side face fin guide plates and one bottom surface fin guide plate; a lean gas outlet passage is formed between the two side face fin guide plates; and a slant angle is formed between each of the two side face fin guide plates and the outer side face of the central pipe. According to the low-nitrogen burner, local high temperature caused by fierce combustion due to excessively high oxygen content at the burner outlet is avoided, the rotational flow formed by the combustible gas and lean gas realizes a backflow area to achieve entrainment of the surrounding air so as to realize low-oxygen combustion, and formation of heating power type NOx is restrained.